Monday, June 30, 2014

Cosmic Ray Flux Related To Atmospheric Temperature

Cosmic rays, a term that includes not just photons but also fast moving particles headed towards Earth, would kill us all were it not for the protective shield provided by our atmosphere.  Analysis of cosmic rays hitting earth are also a key to trying to detect dark matter, the properties of neutrinos, and more.

Seasonal variation in these cosmic rays has often been proposed as a key to distinguishing dark matter derived signals from other data.  But, it turns out that the strength of the shield that the atmosphere provided against cosmic rays is a function of its temperature.

This makes sense.  But, a results from the MINOS experiment quantity this seasonal background factor based on differences in intensity of muon fluxes (which often are produced when cosmic rays strike the atmosphere).  This is important because is strongly suggests like seasonal variation in cosmic ray detection that might otherwise be assumed to be a significant signal, is really just due to atmospheric temperature variations.

Also, detection of sub-GeV energy dark matter signals requires that neutrinos and other cosmic ray backgrounds be well understood.  This kind of stepping stone makes that possible.

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Precision measurements of neutrinos can also serve as a probe of Lorentz invariance violations (i.e. violations of special relativity), that are expected in some quantum gravity theories.  The experimental signatures of Lorentz invariance in neutrino experiments are discussed in another new paper.

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